The State Variable Filter is good option

A project log for XiAleste

XiAleste Next is an 8-bit home computer, which is compatible with software for the Amstrad CPC6128 released on 13 June 1985

h2wh2w 01/06/2023 at 14:360 Comments

This type of filter looks simple enough (so it match to XiAleste project) and very stable result. The image below has all filter modes LP,BP,HP. The coice board will mix those results in different proportions.